HWID
Activation support is added for the WNC edition.
KMS38
Beginning with build 26100.7019, Microsoft fully deprecated clip-based KMS license migration functionality. As a result, KMS38 has stopped working. Detailed info.
KMS38 has now been removed from the MAS script. Users are advised to use HWID or TSforge activation instead.
If you still wish to use it on older Windows versions or keep it for archival purposes, you can download the script from here.
TSforge
From build 26100.7019, Windows will always display and stay at the 180-day remaining KMS grace period if the actual period is longer. KMS4k info is updated as per this change.
Added ESU support for PPIPro (added in 19045.6388).
Fixed an issue in filtering where ESU IDs were not showing in the manual option.
Added a command to refresh the ESU status.
Change Windows Edition
Changed key preference order so that the HWID key can be installed. Thanks to @lava1879 (Magic).
Added [GAC, not LTSC] info for the "IoTEnterprise" edition to avoid confusion with its LTSC edition "IoTEnterpriseS".
Troubleshoot
The script will now auto-select the Quick Repair option for Office 16.0 C2R. Thanks to @YerongAI for the suggestion.
Added more conditions before rebuilding ClipSVC licenses.
Check Activation Status
@abbodi1406 fixed an issue in CAS where, when ADBA is active, KMS Client info was shown.
All
Some other minor improvements in error handling and information.

+ Actions: add action to bring all project FX online one at a time
+ Actions: fix extra MIDI events possibly being added at end of item when applying track FX as new take with MIDI output
+ Actions: add action to open 'choose project' prompt (allows opening multiple projects at once)
+ Actions: add actions to set all project take fx online or offline based on whether the take is active or not
+ Actions: show splash screen when closing projects via action
+ API: add StartPreviewFade(), to immediately fade preview audio in or out
+ Auto-crossfades: fix manually edited crossfades being reset when deleting unrelated media items [t=304510]
+ Automation items: add project setting to choose whether 'Beats (position only)' timebase changes length of automation items (on by default, matching behavior of 7.49 and earlier)
+ Automation items: fix start offset when changing effective timebase
+ Color theme: add theme elements for LPF fade color and blend mode
+ Control surfaces: add Console1 support
+ Debug: add project load time report, accessible via 'projload_report' in debug console
+ Default theme: update send level meter images slightly
+ Fades: clear LPF fade, reset fade curvature when performing various editing actions [t=304275]
+ Fades: improve behavior of 'move crossfade' mouse modifier when editing non-crossfade [t=304426]
+ FX: add preference to control whether pin mappings are loaded when loading FX presets [t=287808]
+ Import: add action to insert all media items in directory
+ Import: add setting and preference to create folder tracks for imported directories
+ Import: recursively import files from subdirectories when dragging a directory into REAPER
+ Import: warn/verify when importing more than 1000 files at once
+ Import: ignore .txt files when drag/dropped into arrange view with other media
+ JSFX: fix showing JSFX pathname when inserting via action/script on Windows [t=304344]
+ Media explorer: set default fade-in/fade-out to 20ms
+ Media explorer: support either fade-in or fade-out (or both/neither) for preview audio (replaces option to crossfade)
+ Media import: don't prompt to match empty project tempo to media if the project tempo is already set to the media tempo
+ Media import: simplify tempo-match preferences
+ MIDI editor: add option to draw CCs as gray
+ MIDI editor: add option to hide CCs in secondary contexts
+ MIDI editor: add preference for opacity of secondary editable contexts, extend opacity configuration range for inactive items
+ MIDI editor: show note names from tracks that MIDI is routed to, if any
+ Mouse modifiers: add ripple options for edge edits (only affects editing right edges)
+ Mouse modifiers: modifier to adjust item edge without changing fade only applies to pre-existing fades [t=304351]
+ Paths: increase maximum length of VST/LV2/CLAP plug-in path lists to 64k
+ Peaks: draw first sample of peaks over left border of containing media item
+ Peaks: fix errors where the first sample of media file may get skipped (7.39 regression) [t=304010]
+ Portable installs: fix issue in new 7.50 feature where VSTs would be rescanned even if skip requested by user
+ Project backups: add option to auto-save unsaved projects, will also save at exit and be available (if configured) when re-launching REAPER
+ Project bay: properly handle dragging items into 'add new track' area of project
+ Project bay: support creating folder tracks from project bay folders
+ Project load: add checkbox to load project with FX online, then bring FX online one at a time
+ Project load: add FX offline/online options to import RPP dialog
+ Project load: display loading progress in splash screen
+ Project load: improve loading speed of projects that have many per-take FX
+ Project settings: add project setting (advanced tab) to always load project with FX offline, or bring FX online one at a time
+ Render: fix brickwall limiting to master mix when also rendering master mix and normalizing to master mix [t=304595]
+ REX: fix potential error when importing as beat slices and source tempo is lower than project tempo [t=304388]
+ REX: when importing as beat slices from media explorer with time selection set, import slices if they start within the time selection, and do not truncate the end of the slices
+ Searching/filtering: better handle case folding of UTF-8 codepoints up to U+800 [t=302713]
+ Searching/filtering: improve synonym case folding support for localized synonyms
+ Shutdown: improve shutdown process (display splash screen while unloading project), better compatibility with some plug-ins/control surfaces
+ Spectral edits: add actions to bypass/solo/delete selected spectral edits, reset/adjust gain of edit
+ Spectral edits: add new preferences page to configure defaults for new spectral edits
+ Spectral edits: control+clicking an edit allows multi-selection of edits
+ Spectral edits: faster drawing updates when modifying edits
+ Spectral edits: improve selection behavior, deselect spectral edits in other items when selecting, etc
+ Spectrogram: add high resolution spectrogram view (when sufficiently zoomed-in, zoom threshold is configurable in preferences)
+ Spectrogram: add mousewheel/MIDI CC/OSC assignable actions to adjust brightness/contrast/curve/frequency curve
+ Spectrogram: fix slightly-incorrect display (skipping one very high frequency bin)
+ Toolbars: prevent overly-large images from resizing toolbar editor too large
+ Toolbars: allow larger toolbar images (7.50 change partially reverted) [t=304328]
+ Undo: allow longer undo messages [t=303957]
+ Undo: support longer track names/etc for FX, envelope context messages