If TSE License is pain for you, read this!
The grace mode is 90 Days. So you may not notice that you are in the grace mode...until the next 91 Days!.
TS Server may auto locate the license server, but you can set it manually; see KB 239107.
The big road:
Add the following value:
Data type: REG_SZ
Data value: ServerName
To make a workstation working again immediately, you can reset it's token. Upon the next connection, the station will generate a new token that will be in grace mode for 90 days.
The key to delete:
If you are on a per user mode, TSE doesn't count users. So it's just a declarative status.