SQL Server memory constantly going up, from 1GB RAM used to 7GB in a week

SQL server is meant to use as much ram as it can get its hands on. SQL server is also incredibly smart. We have database servers with RAM ranging from 2Gb to 96Gb and not once, ever, have I had to step in and start managing RAM manually, and most of them sit at 99.5% utilisation.

The simple fact is that SQL Server running with 1Gb of consumed memory is going to be a lot slower at reads than an SQL server running with 96Gb of consumed memory.

Unless you are sharing the SQL server roles with other memory intensive roles, then just leave it alone. It will never use more memory that is available in the system, and if it hits 99% utilisation then great - you've created a large cache and things will be faster from now on.

Typically you'll want to allocate 1-2 Gigs of RAM for the OS so that the OS has RAM to work with. The SQL Server can then have the rest of the memory.